Perennials are great plants to have, because you don’t have to buy them every year. They become dormant in the cold and when the weather warms back up, they start budding again as if a magic fairy sprinkled them with life dust. However, not all perennials can survive the winter months, especially the cold temperatures in northern regions.
So, what’s the point in buying perennials if they are just going to die? Well, they won’t die if you overwinter them! Overwintering is the practice of protecting your plants during the winter months, so that they come back in next growing season.
There are plenty of ways to protect your plants including keeping the plant alive and moving it to a warm place, taking root cuttings to plant for the next growing season, and allowing the plant to go dormant and storing it in a cool, dark place.
Growing Indoors
If you have a sunny window or a sun room that stays around 60-70 degrees, you can keep your plants growing and possibly even blooming all the way until spring. It will take some time for the plants to adjust to living indoors, but if you bring them in before the temperature drops too much, they will acclimate. The plants will need about 12 hours of sunlight each day, and will not be happy if the temperature drops below 40 degrees. But, they will enjoy some light misting and good air circulation.
You also have the option of storing them in a coldframe outside to save on space in your home.
Taking Clippings
Another technique is to take clippings in the fall and let the “mother” plant die. Cuttings take up less space than entire plants and can eliminate the possibility of pests.
If the stems are young and succulent, and they haven’t become dried and woody, you can preserve them in water on a windowsill. Once roots have formed, you can plant them in a shallow pot. Keep them in a well-lit area and provide fertilizer regularly.
Forcing Dormancy
If you don’t have the space for houseplants or the time to care for plants during the winter, forcing dormancy is a good option. You can clip the plant at the bulb or root and keep the entire pot in a cool area indoors. Make sure the soil stays a little moist. For woody plants, just bring the entire plant inside: there’s no need to cut it back until spring.
You can also dig up the bulb or roots of tender plants. After digging them up, wrap them in moist newspaper and store them in a trash bag in a dark, cool place. They can be replanted in the spring in a sunny window with lots of fertilizer.
Some perennials go dormant by themselves, but still need protection and you might not be able to bring them inside. In this case, you can cover them with a thick layer of mulch to keep them warm. Shrubs and vines can even be buried in trenches for protection.